<html>

	
	<body>
			<ul>null</ul>
			<script>
				var a ="1"
					a+="2"  // a = a + "2"  => a = "12"
					a+="3"  // a = a + "3"  => a = "123"
					a+="4"  // a = a + "4"  => a = "1234"
				// console.log(a)
				

				var ul = document.querySelector("ul")
				ul.innerHTML += `<li>1</li>` // = > ul.innerHTML = ul.innerHTML +  `<li>1</li>`  => "<li>1</li>"
				ul.innerHTML += `<li>2</li>` // = > ul.innerHTML = ul.innerHTML +  `<li>2</li>`  => "<li>1</li><li>2</li>"
				ul.innerHTML += `<li>3</li>`
				ul.innerHTML += `<li>4</li>`
				ul.innerHTML += `<li>5</li>` // => ul.innerHTML = ul.innerHTML +  `<li>5</li>`  => "<li>1</li><li>2</li><li>3</li><li>4</li><li>5</li>"
				
			



			
			</script>
	</body>

</html>